The present invention relates to tape splicing apparatuses. More particularly, the invention relates to a tape butt-joining apparatus.
The term "tape" as herein used is intended to mean relatively thin flexible belt-shaped materials, for instance 2-250 .mu.m, of small in width, for instance 3-55 mm, such as plastic films made of polyesters such as polyethyleneterephthalate, polyethylene-2 and 6-naphthalate, polyolefins such as for instance polypropylene, cellulose derivatives such as cellulosetriacetate and cellulosediacetate, or polycarbonate; or metal sheets of copper, aluminum, zinc, etc.; or paper such as baryta paper or synthetic paper. Furthermore, the term "tape" includes the above-described flexible belt-shaped materials on which magnetic recording layers, photosensitive layers, colored layers, or the like are formed by coating. Examples of such flexible belt-shaped materials are magnetic recording media such as magnetic tapes, photographing photosensitive materials such as motion picture films, and leader tapes which are transparent or semi-transparent and are connected to the ends of magnetic tapes or photographing films.
The tape described above is shipped or used after it has been wound to a predetermined length on a winding core member which is suitably designed according to the specific intended use or the tape is wound on one of the two winding core members to which both its ends have been attached.
Heretofore, in the process of winding the tape on a winding core member to produce a tape roll having a predetermined length, when the tape of a first stock tape roll from which the tape is being supplied has run out, a second stock tape roll is provided to continue to supply the tape. The ends of the present and preceding tapes must accordingly be joined together with splicing tape or the like to produce a tape roll of the desired length. Also, it may be desired to join tapes of different characteristics such as a magnetic tape and a leader tape to produce a tape roll having a predetermined desired length.
In the above-described tape roll forming or manufacturing process, a method in which the tapes are butt-joined is preferable to a method in which the tapes are joined with the end portions thereof overlapped so that higher tape running speeds may be used in tape utilizing equipment such as magnetic recording and reproducing devices, cameras, developing devices or projectors. A variety of tape butt-joining methods and apparatus have been proposed in the art. A typical example of a conventional tape butt-joining apparatus is shown in FIG. 1. First and second movable tape receiving stands 4 and 5 having guide grooves are arranged radially on the front surface of a rocking supporting plate 3 which is in the form of a sector and is rockable around its supporting shaft 2. The receiving stands 4 and 5 are alternately brought into alignment with a stationary tape receiving stand 1 with a guide groove by rocking the plate 3 so that tapes retained by suction in the guide grooves of the receiving stands 1, 4 and 5 are butt-joined.
The operations of various members of the conventional apparatus will be described in more detail. First, the first movable receiving stand 4 is aligned with the stationary receiving stand 1 by swinging the rocking supporting plate 3. A first tape T.sub.1 which is supplied from a stock roll (not shown) positioned upstream of the first movable receiving stand 4 is continuously delivered in the direction of the arrow A through the first movable receiving stand 4 and the stationary receiving stand 1 to a winding section (not shown) located downstream of the stationary receiving stand 1. If the stock roll of the first tape T.sub.1 runs out before the length of the tape wound reaches a predetermined value, the tape T.sub.1 is retained by suction on the bottoms of the guide grooves the first movable receiving stand 4 and the stationary receiving stand 1 and the tape T.sub.1 is cut by moving a tape cutting knife 6 along a small gap C between the receiving stands 4 and 1. Thereafter, the second movable receiving stand 5, which retains by suction on the bottom of its guide groove a second tape T.sub. 2 drawn from a stock roll, is aligned with the stationary receiving stand 1 by swinging the rocking supporting plate 3 so that the first and second tapes T.sub.1 and T.sub.2 are in abutment with each other over the gap C without overlapping each other. Thereafter, a splicing tape T.sub.3 provided above the butt joint in advance is bonded to the butt-joint region of the tapes T.sub.1 and T.sub.2 and then the second tape T.sub.2 is wound upon the first tape T.sub.1.
In another example of a conventional tape splicing apparatus, the first and second movable receiving stands 4 and 5 are arranged parallel to one another in the same plane and the receiving stands 4 and 5 are moved back and forth with respect to the stationary receiving stand 1 whereby the first and second tapes T.sub.1 and T.sub.2 switched over.
Recently, the operating speed of tape processing equipment has been increased and accordingly the tape guide mechanisms in recently designed equipment have become more intricate. Commensurate with this development, the tape should be capable of running at higher speeds. However, it is difficult for tape spliced using a conventional tape splicing apparatus to meet this requirement due to several drawbacks. Namely, the first and second movable receiving stands 4 and 5 and the stationary receiving stand 1 have guide grooves which guide the tapes T.sub.1 and T.sub.2 in the direction of the arrow A and which limit the positions of the tapes T.sub.1 and T.sub.2 in the widthwise direction. In order to allow the tapes T.sub.1 and T.sub.2 to run smoothly in the direction of the arrow A, the width of each of the guide groove cannot be made equal to the width of the tapes T.sub.1 and T.sub.2. That is, the width of each guide groove is somewhat larger than the width of the tapes. The difference in width between the guide groove and the tapes causes the edges of the tapes to shift at the joint. Thus, the tape butt-joining accuracy is limited and it is also difficult to provide adequate tape running characteristics. Furthermore, if tapes are joined with a conventional apparatus using a very quick action, then frequently air bubbles will be trapped between the spliced tapes thereby reducing the strength of the tape at the butt-joint and decreasing the tape running characteristics.
In view of the foregoing, the inventors have conducted intensive research to provide a tape splicing method and an apparatus for practicing the method in which the tape butt-joining accuracy is remarkably improved.
Accordingly, an object of this invention is to provide a tape splicing apparatus in which all of the drawbacks accompanying a conventional tape splicing method or apparatus have been eliminated and with which tapes can be spliced with a high butt-joint accuracy with a relatively compact mechanism.